A current trend in agriculture is that the number of operators has decreased while the number of acres farmed by an operator has increased. This in turn requires a higher efficiency of operation by the operator on multiple fronts. One way of increasing efficiency is to increase the size of the equipment which is used to farm the land. As the working width of various implements pulled by a traction unit (e.g., tractor) has increased in size, the attendant problems with transporting such large implements over roads has needed to be addressed.
One way of minimizing the frontal profile width of an implement is to construct the frame in multiple discrete sections, with at least one of the sections folding relative to another.
In the case of an agricultural seeding machine such as a row crop planter, the individual row units are typically ground driven from a main drive shaft. It is not desirable to separately ground drive the center section from the folding frame section since the operating variables such as tire pressures, etc. may vary and cause different ground drive speeds. As one frame section unfolds and aligns with the other, the main drive shaft generally is in end-to-end and coaxial alignment with the driven shaft carried by the other frame section. One solution for transferring power from the drive shaft to the driven shaft is for the operator to dismount and manually couple the drive shaft with the driven shaft.
Another example for coupling a drive shaft with a driven shaft in an agricultural implement is disclosed in U.S. Pat. No. 4,690,260 (Landphair), which is assigned to the assignee of the present invention. Such a coupler is known as a “tomahawk” coupler and automatically engages and disengages the drive shaft and the driven shaft when the frame member is unfolded to the operational position. This type of coupler for automatic engagement and disengagement was a step forward in the art and is effective for the intended purpose.
What is needed in the art is an agricultural seeding machine having a coupler which automatically engages and disengages a drive shaft and a driven shaft where one frame member is not only moveable between a folded and an unfolded position, but is also moveable in a generally vertical direction corresponding to the contour of the ground.